Characterisation of transparent ITO emitter contact InP/InGaAs heterojunction phototransistors

The electrical, optical and spectral responses of optically transparent emitter InP/InGaAs heterojunction phototransistors (HPTs) fabricated using Indium Tin Oxide (ITO) are presented. These HPTs showed significantly increased optical responsivities while: the electrical characteristics were similar to their respective opaque counterparts. Responsivities of 28 A/W at 1310 nm for the InP/InGaAs HPTs were obtained. The spectral responses of these phototransistors were simulated and compared with the measured results and good correlation between the experiments and the theoretical models were obtained.